Surface gap igniter plug for gas turbines



July 14, 1953 J. o. SARTO SURFACE GAP IGNITER PLUG FOR GAS TURBINES 2 Sheets-Sheet 1 Filed May 24. 1949 INVENTOR. 72774 Q Jdri a. BY W W July 14, 1953 J. o. SARTO 2,645,082

SURFACE GAP IGNITER PLUG FOR GAS TURBINES Filed May 24. 1949 2 Sheets-Sheet 2 E-E- w INVENTOR. \fZrVfid O, Jarfo.

BY 2mm /W 17770 IPA/I76 Patented July 14, 1 953 SURFACE GAP IGNITER PLUG FOR GAS TURBINES Jorma 0. Sarto, Walled Lake, Mich, assignor t Chrysler Corporation, Highland Park, Mich, a

corporation of Delaware Application May 24, 1949, Serial N 0. 94,954

Claims.

The present invention relates to igniter structure, and more particularly to an ignition device for use with certain combustion chambers and spray burners.

An object of the invention is to provide an igniter adapted to fit flush with the interior walls of a combustion chamber, the electrodes thereby being unexposed to the direct path of the deteriorating combustion gases and the path of the gases at the same time being unobstructed by projecting-electrodes.

Another object of the invention is the provision of a ground electrode of sufiicient mass to protect and shield the center electrode of an igniter as much as possible and rapidly conduct away heat from the inner vicinity thereof.

A further object of the invention is to provide an electrode gapway through which may be passed a flow of cooling medium under pressure.

Yet another object is the provision of an igniter relatively free from tendency to accumulate carbon deposits and the like.

Yet a further object is to provide an igniter construction not susceptive to premature failures at high temperatures, but rather of a rugged and long lasting character.

Still another object of the invention is to produce a simple and relatively easy fabricated igniter such as will lend itself to the economic appeal of inexpensive manufacturing technique.

Further objects and advantages of the invention will be made evident throughout the following part Of the specification.

For the purpose of disclosing my invention I have illustrated certain embodiments thereof in the accompanying drawings in which:

Figure 1A is a longitudinal sectional View of the igniter structure of the present invention and an application therefor; Figure 1B is a transverse sectional view of the igniter structure taken along the lines |B-IB in Figure 1A;

' Figure 2 is an enlarged longitudinal transverse section of a modified form of igniter construction; and

Figure 3 is a fragmentary view taken along line 3-3 of Figure 2 with certain parts broken away for purposes of clarity.

The igniter construction l0 of Figures 1A and 13 may be used to good advantage in the burner shown and claimed in the copending application of Samuel B. Williams, Serial No. 715,873, filed December 12, 1946, now Patent No. 2,603,064. Briefly the operating principles of this burner are as follows. Along the inner passageway formed by outer tube 40 a supply of a combustion-supporting medium is forced under pressure and led into an inner tube 42 through passages defined by frusto-conical sections 44 held in place in tube it by means of suitable mounting brackets 5. Wall 46 is belled in at one end to provide an end wall formed with suitable flanges for defining an opening 48. Adjacent opening 58 is another opening 31 defined by suitable flange portions M. Into the first described opening is adapted to fit a spray nozzle 50, Spray nozzle 50 may be of a type shown in Figure 2 whereof bypassed fuel is adapted to be led away by a passage 52 in the holden'the inlet fuel having gained entry through another passage 54 in the holder. From passage 54 the inlet fuel is conducted to an annular chamber 55 and then passed forward respectively through annular chamber 58, passages 62, and annular chamber 64 to tip 69 of the nozzle. Tangential swirl passages 66 are formed in the tip for spinning in fuel into swirl chamber 68 of the tip. From swirl chamber 68, fuel may be expelled in one direction through ejection orifice l2 and into the chamber defined by Wall 46 for producing therein a fuel spray pattern. In the opposite axial direction from swirl chamber 68 a certain amount of bypassed fuel may be led through passage 14 into another passage 16 communicating with a rear chamber 18 in the nozzle holder. From chamber 18 the fuel is allowed to return to the fuel system through the bypass passage 52.

By way of return to Figures 1A and 113, downstream of corrugated portion 43 of the outer tube it may be observed members 4'! and 49, curved in conformity with the purposes specified in the aforementioned Williams application Serial No. 715,873 filed December 12, 1946, now Patent No. 2,603,064. It is, of course, to be understood that the igniter construction of Figure 1 does not necessarily have to be used in conjunction with the burner of the said Williams application, for it may be used as igniter for other installations. Also it is not limited in use to ordinary external combustion devices but may also be used for certain other purposes in connection, for example, with internal combustion devices. In fact, the igniter construction may be used in any device that requires a spark to be produced in some fluid or fluid-like medium.

Igniter it] of Figures 1A and. 1B will be observed to comprise an end member or fiange l2,

which defines an opening [4 in surrounding relation to member I6. The ensuing gap may be of an annular configuration, it being the desired operation of the device to pass a spark across the gap between the electrodes. Wall portion I8 attached to end member I2 is received by the flange portion 4| and lies laterally of an exposed segment of member I6 in spaced relation. A ceramic sleeve 22 is adapted to fit around member I6 in spaced relation to another wall portion 24. The wall portion I8 and the wall portion 24 in diametrically opposed relation thereto and parallel therewith, together form portions of a section of the igniter casing and will be seen in section together to constitute a pair of spaced parallel wall portions of unequal length of which the one nearer the nozzle is the longer. Ceramic member 25 is received in contacting and sealed engagement within the wall portion 28 for firmly holding member I6 in proper relation to the rest of the device. Formed in wall 24 is an opening 25 through which the air occupying the space within outer tube may be led and thence conducted along annular wall portions 24 and I8 out through the spark opening between members I4 and IS. The air supply in the burner may come from some conventional source such as a compressor, not shown. A radiating member 32 is shown attached to wall 28 and in turn is secured to a bracket 34 attached to tube 40 by suitable fasteners 36-. Power supply 38 is diagrammatically shown as the source of electric potential. impressed upon electrode post 39 by means of which member It is energized.

Inasmuch as the combustion-supporting medium needs must pass through the restricted openings formed by members 44, the pressure existing inside the inner tube 42 is less than the pressure within the outer tube 45. Hence air will be forced through opening 25 of the igniter into the chamber between the shell electrode walls and the inner electrode and ceramic and expelled under pressure through the spark gap restriction between members I4 and I6 into the lower pressure region within tube 42. The effect of the resulting high velocity flow of medium upon the spark has been observed to be such that the family of arcs which exist normally between members It and I6 is not diminished but merely bowed out as it were into the interior of the chamber formed by wall 46. Under certain cir cumstances this family of. arcs may even be intensified somewhat. One result, of course, is that no carbon deposits tend to form within the spark gap to any appreciable extent. It also follows that the operating temperature of the electrodes may be kept down. and that the spark gap is in effect removed from too intimate a relation with the interior structure of the ignition device. As a further means of maintaining the igniter at as relatively low operating temperature as practicable, end member I2 will be seen to assume a rather bulky and massive form such as will desirably conduct away heat from the immediate vicinity of the spark gap and transmit it to other and cooler portions of the burner or other machinery to which it might be applied.

In Figures 2 and 3 are shown enlarged views or an igniter construction of a slightly modified form. The spark plug or igniter device II will be seen to have a solid wall portion I24 in the place of the previously apertured wall shown in connection with the preceding embodiment. A shoulder I2I provided in wall I28 is adapted to cooperate with an opposed shoulder I32 formed on a fitting I21 to insure a gas tight seal about ceramic member I26. Suitable adjustability as relates to-the reception of fitting I21 in sleeve I28 may be achieved through provision of threading I29 or the like. Radiating flange I32 on igniter IIO may be received upon a suitable gasket I3I which rests upon an outer tube of the combustor I40. The spark gap shown between members H4 and I It may be similar to the originally described form, of an annular configuration. Openings may be provided in radiating flange I32 at I33 and I35 for suitably fastening the igniter directly to the outer tube I40 of the burner.

Operation of the embodiment of Figures 2 and 3 is substantially the same as that of the foregoing embodiment such as would occur if no air were forcibly passed in flow therethrough. The are within the spark gap between members H4 and H6 will tend to describe more or less a straight or direct path between the aforesaid members as contrasted with creating any bowed effect.

In both of the illustrated forms selected for describing the invention, it will be noted end electrode members I2 and I I2 of the respective ignition devices serve to surround and in effect protect the smaller and less massive electrodes I6 and H6. Neither electrode projects into the air flow or fuel flow taking place within the inner tube 45 and as a consequence does not occasion the deposit of carbon at any locations therein. The resulting streamlining is conducive not only to the effect that no undue turbulence is created within the inner tube 46, but that the spark gap itself is removed in effect from the directly impinging spray particles of hydrocarbon and less tendency exists for carbon and other deposits to accumulate in the spark gap. It has been experimentally determined that upon relieving a combustion tube of unnecessary obstructions the degree of mixing of the combustion-supporting medium and the fuel is greatly increased and that an overall efficiency and fuel economy will result.

Although I have herein shown and described m invention in simple and practical form, it is to be recognized that certain parts or elements thereof are representative of other parts, elements, or devices which may be used in substantially the same manner to accomplish substantially the same results; therefore it is to be understood that the invention is not to be limited to the details disclosed herein and that the invention can be embodied in other forms without departure from its spirit.

What is claimed is:

l. The combination of an elongated high temperature gas turbine combustor incorporating a flame tube assembly having a flame chamber and an air chamber adapted to contain air under pressure surrounding the flame chamber, a discharge dome at one end of the flame chamber having a smooth side wall, an end wall, an opening opposite said end wall, a conduit having spray aperture means protruding centrally into said discharge dome and extending in a direction to direct a stream of spray towards said opening, and means at the sides of the flame chamber forming passageways arranged to direct pressure air from the air chamber inwardly into the relatively lower pressure region of said flame chamber and in a direction upstream with respect to the stream of spray, and igniter means incorporated in the flame tube assembly in said air chamber and comprising a plurality of spark electrode portions substantially flush with the smooth side wall of said discharge dome, and forming a surface gap in the surface thereof, said surface gap being in the form of a continuous circular path of revolution formed between the respective electrode portions aforesaid and disposed in a laterally ofiset position with respect to said spray aperture means and said pressure air passageways.

2. In combination with the wall structure of a high temperature gas turbine burner having tubes one without the other and being provided with a general supply of air under pressure therebetween, means forming a dome at one end of the inner tube, fluid flow path means in the sides of the inner tube for passing air from outer tube along the interior of the inner tube in the direction of said dome, fluid flow path means for introducing fuel particles into said dome, and means forming an opening in the side of the inner tube effectively intervening between said fluid flow path means for air and fuel particles and being generally in the path of fluid flow, an encased igniter disposed between said tubes having an end received in said opening and including sparking electrodes arranged to define a restrictive annular spark gap, said annular gap and said opening being disposed substantially in a common plane so as to expose the electrodes to the fluid flow aforesaid without protruding thereinto, and an opening in the case of the igniter for admitting a portion of the general supply of air between tubes, through the igniter case and restrictive annular spark gap such as to cause the spark to bow out into the space between said dome and said fluid flow path means for air.

3. In combination with the wall structure of a high temperature gas turbine burner provided with tubes one without the other having means forming a dome at one end of the inner tube, fluid flow path means in the sides of the inner tube for continuously passing air under pressure from outer tube into the lower pressure region within and along the interior of the inner tube in the direction of said dome, means forming an opening through the side of the inner tube intervening between said passage means and said dome, and fluid flow path means for continuously introducing liquid fuel particles into said dome, an encased igniter in the space between said tubes having an end in said intervening opening and including electrodes therein arranged to define an annular restrictive gap, said gap and said opening being disposed substantially in a common plane so as to be exposed to the continuous fluid flow aforesaid without protruding thereinto, said encased igniter having communication including means forming an opening in the side thereof for leading pressure air from the space between tubes to said annular gap for expelling air under pressure through the annular spark gap into the lower pressure region of the inner tube.

4. In combination with the wall structure of a high temperature gas turbine burner provided with tubes one without the other having means forming a dome at one end of the inner tube, fluid flow path means in the sides of the inner tube for continuously passing pressure air from outer tube into the lower pressure region of the inner tube and along the interior of the inner tube in the direction of said dome, fluid flow path means for continuously introducing liquid fuel particles into said dome, and means forming an opening in the surface of the side of the inner tube intervening between said fluid flow path means for air and said dome and being generally adjacent the fluid flow, an encased igniter in the space between said tubes having an end in said intervening opening and including electrodes therein arranged to define a restrictive gap disposed substantially flush with the surface of the side of the inner tube, said surface gap and said opening being disposed substantially in a common plane so as to be exposed to the fluid flow aforesaid without protruding thereinto, said igniter having an opening in the case thereof adapting the igniter to provide continual communication between the space between tubes and the said elec trode gap.

5. The combination of an elongated high temerature gas turbine combustor incorporating a tube assembly having a flame chamber and an air chamber adapted to contain air under pressure surrounding the flame chamber, a discharge dome at one end of the flame chamber having a smooth side wall, an end wall, an opening opposite said end wall, a conduit having spray aperture means protruding centrally into said discharge dome and extending in a direction to direct a stream of spray towards said opening, and means at the sides of the flame chamber forming passageways arranged to direct pressure air from the air chamber inwardly into the relatively lower pressure region of said flame chamber and in a direction upstream with respect to the stream of spray, and a plurality of spark electrodes forming a surface gap substantially flush with the surface of said smooth side wall of the discharge dome, said surface gap being restrictively formed according to a relatively radially narrow continuous circular path of revolution defined by the electrodes and disposed intermediate said spray aperture means and said pressure air passageways, said plurality of electrodes having means cooperating therewith to define a passage leading pressure air from the air chamber to said gap whereby to expel air through the circular path of revolution thereof into the lower pressure of said flame chamber.

J ORMA O. SARTO.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,098,637 Ranch June 2, 1914 2,096,199 Rabezzana Oct. 19, 1937 2,162,572 Block June 13, 1939 2,305,208 Trammell et al. Dec. 15, 1942 2,443,556 Fairbanks June 15, 1948 2,465,092 i-Zarkness et a1. Mar. 22, 1949 2,526,169 Steeg Oct. 17, 1950 FOREIGN PATENTS Number Country Date 585,763 Great Britain Feb. 24, 1947 

